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Lightwave Technology, Journal of

Issue 7 • Date July 1987

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Displaying Results 1 - 25 of 31
  • [Front cover and table of contents]

    Publication Year: 1987 , Page(s): 0
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    Freely Available from IEEE
  • Fiber-coupler fabrication with automatic fusion-elongation processes for low excess loss and high coupling-ratio accuracy

    Publication Year: 1987 , Page(s): 910 - 915
    Cited by:  Papers (10)  |  Patents (25)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4581 KB)  

    A novel fiber-coupler fabrication system which automatically processes fusion and elongation is presented. Not only conventional single-mode fiber couplers but also polarization-maintaining fiber couplers with excellent characteristics such as excess losses less than 0.11 dB and coupling-ratio accuracy better than 1.3 percent were obtained. In addition, it was confirmed that polarization crosstalk for polarization-maintaining fiber couplers in the present system was lower than that for the conventional manual method. The fabrication yield and reliability of the present system have been much higher than those of the conventional method and the processing time for fabrication could also be reduced. View full abstract»

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  • [Back cover]

    Publication Year: 1987 , Page(s): c4
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    Freely Available from IEEE
  • Time-domain addressing of remote fiber-optic interferometric sensor arrays

    Publication Year: 1987 , Page(s): 1014 - 1023
    Cited by:  Papers (19)  |  Patents (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3560 KB)  

    This paper describes and analyzes a particular application of high duty-cycle time-division multiplexing to the separation and identification of signals from an interferometric sensor array. Using the method discussed here, the coherence length of the laser is no longer a severe design constraint. Also, the source phase-induced intensity noise which limits some other multiplexing methods may be overcome, leading to a higher sensitivity. The arrays of all-passive remote sensors exhibit minimal crosstalk between sensors, and have downlead insensitivity. A synthetic heterodyne demodulation technique prevents environmentally induced signal fading. Analysis includes coupling ratios for all directional couplers in the system, signal and noise spectra, minimum detectable phase shift, and the effect of ac coupling on noise and crosstalk. An experimental all-fiber implementation of a two sensor array has yielded a measured sensitivity of approximately 10 μrad/ \sqrt {Hz} over a range of signal frequencies, and a crosstalk level of better than 55 dB. View full abstract»

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  • Trench depth measurement system for VLSI DRAM's capacitor cells using optical fiber and michelson interferometer

    Publication Year: 1987 , Page(s): 881 - 887
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2480 KB)  

    A simple method to precisely measure the trench depth of VLSI DRAM's capacitor cells is presented. The measurement system uses a Michelson interferometer and a white light source. The trench depth is transformed into the optical path difference between the central peak and one of sideband peaks produced during one-way scan of a mirror in a Michelson interferometer. The measurement error was within \pm0.2 \mu m for trench depths of 2-5 \mu m. The multimode fiber used in the system facilitates wafer setup so that the system can be introduced into an in-process measurement system. View full abstract»

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  • Observation of coherence effects in a quasi-monochromatic fiber-optic gyroscope

    Publication Year: 1987 , Page(s): 1024 - 1026
    Cited by:  Papers (2)
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    The sensitivity reduction resulting from a loss of fringe visibility due to the limited coherence of the broad-band source in a fiber-optic gyroscope is observed. The experimental data is well described by coherence theory assuming a Gaussian spectral shape for the superluminescent diode source. View full abstract»

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  • Upper limits of soft X-ray transmission factors for curved hollow-core glass fibers

    Publication Year: 1987 , Page(s): 877 - 880
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1176 KB)  

    This letter presents a method to calculate the upper limits of soft X-ray transmission factors for curved hollow-core fibers. The limits of fused-quartz, lead-glass, and soda-glass fibers were calculated as a function of wavelength. View full abstract»

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  • Linearity stablized fiber-optic thermometer using pseudo-heterodyne phase detection

    Publication Year: 1987 , Page(s): 961 - 966
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2280 KB)  

    A temperature sensor using a fiber-optic Fabry-Perot interferometer is described. A pseudo-heterodyne detection scheme is adopted to read the light phase difference in the Fabry-Perot interference output. A higher harmonic components comparison method is used to stabilize the system and to increase detection linearity. This system realizes not only highly sensitive temperature sensing with good linearity and minimal adjusting error, but also application to the sensing of other physical quantities such as vibrations. Additionally, the signal-to-noise ratio and distortion of the detected signal are investigated as functions of fiber end reflectivity. These results will be useful in designing a high performance fiber-optic Fabry-Perot thermometer. View full abstract»

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  • A novel intrinsic multimode fiber-optic sensor for the detection or monitoring of microwave power

    Publication Year: 1987 , Page(s): 888 - 894
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2104 KB)  

    A graded-index silica multimode fiber with an acrylate primary coating has been shown to act as an intrinsic sensor of microwave power. When under the influence of a microwave field, the fiber absorbs a small fraction of microwave energy and this alters the propagation condition for transmitted laser light (632.8 nm). This alteration is manifested in the speckle pattern which is projected, after transmission, from the cut end of the fiber, and is recorded either by an optical detector or by visual observation. The rate of change of the speckle pattern is the important feature. The sensitivity of the effect increases as the microwave power increases, as the fiber length increases, and when the fiber is coated with conducting silver paint. Microwave powers, transmitted at 2.45 GHz in a rectangular waveguide is in the range 0.07-700 W were detected with an accuracy of better than 2 dB. These power levels correspond to electric field levels of 2.8 \times 10^{2} V . m-1and 2.8 \times 10^{4} V . m-1at the position of the fiber. The results are briefly compared with recent similar observations using a silica single-mode fiber as the sensor and an interferometer as detector. Discussions relate to use of the speckle pattern for detection and to possible applications. View full abstract»

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  • A miniature fiber-optic probe for optical particle sizing

    Publication Year: 1987 , Page(s): 967 - 971
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    A miniature fiber-optic probe has been developed for in situ particle size measurements. The probe is based on a near-forward scattering technique and makes use of a two-color seheme in which one wavelength is used for the size measurement while the second wavelength is used to monitor the presence of a particle in the center of the scattering volume. Tests of the probe have shown particle size range and sensitivity similar to that observed using fixed lens train systems but with the advantages of portability, ease of remote access, anti inherent alignment stability. View full abstract»

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  • A new heterodyne fiber-optic gyroscope using electrooptic frequency shifter

    Publication Year: 1987 , Page(s): 986 - 989
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    In this paper, a novel heterodyne detection technique of rotation rate is described. This technique uses highly birefringent single-mode fiber and an electrooptic frequency shifter for a heterodyne interferometric system, and thus releases the use of acoustooptic devices and also the nonreciprocity which usually exists in a heterodyne fiberoptic gyroscope. Initial experimental results show a good linearity of the scale factor. View full abstract»

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  • Drift of an optical fiber gyroscope caused by the Faraday effect: Experiment

    Publication Year: 1987 , Page(s): 997 - 1001
    Cited by:  Papers (3)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1112 KB)  

    Mechanism of the drift generation by the Faraday effect in the optical fiber gyroscope with polarization maintaining fiber coil is studied in the experiments. The results are in good agreement with the theory which we presented previously. The presence of the fiber twist component whose period is just equal to one turn of the polarization-maintaining fiber coil is shown experimentally to cause the drift. The reduction of such a special twin component is essential to reduce the drift caused by the Faraday effect. View full abstract»

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  • A microbend horizontal accelerometer for borehole deployment

    Publication Year: 1987 , Page(s): 993 - 996
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1008 KB)  

    A highly sensitive microbend horizontal fiber-optic accelerometer has been designed, built, and tested. This particular model is aimed at deployment in seismological research where minute accelerations must be detected. The device uses a cantilever beam and the compliance of an optical fiber mounted between deforming teeth to act as the springs in the accelerometer's spring-mass system. Acceleration is detected by sensing the movement of the mass relative to the case through the changes in the intensity of light propagating through the deformed fiber. Accelerations as small as 5 μg at 1 Hz have been detected with a dynamic range in excess of 90 dB. View full abstract»

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  • Optical rotation sensing by the geometric effect of fiber-loop twisting

    Publication Year: 1987 , Page(s): 916 - 919
    Cited by:  Patents (1)
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    An optical technique for sensing a rotation angle is described and experimental results are presented. When a loop of an ideal fiber that exerts no linear birefringence is deformed into a nonplanar curve, the azimuth angle of linearly polarized light propagated in the fiber is rotated. The technique is based on this effect of geometric polarization rotation in an optical fiber. A twisted single-mode fiber is substituted for the ideal fiber. Experimental results include studies of polarization rotation and variations of light propagated in a loop of a twisted single-mode fiber under deformation. View full abstract»

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  • Phase-sensitive radio-frequency magnetic probe using laser diode and optical fiber

    Publication Year: 1987 , Page(s): 906 - 909
    Cited by:  Papers (1)
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    Characteristics are described of a novel probe sensitive to the amplitude and phase of the radio-frequency magnetic field which is composed of a laser diode linked with a small loop antenna, an optical fiber, and a phase-sensitive detection instrument. The probe is highly sensitive and is radio-frequency interference free. The minimum detectable radio-frequency magnetic field is 10 μA/cm (38 nW/cm2in power density). View full abstract»

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  • A simple frequency domain multiplexing system for optical point sensors

    Publication Year: 1987 , Page(s): 1002 - 1007
    Cited by:  Papers (1)
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    A new technique for the multiplexing of intensity modulated optical fiber point sensors using a frequency domain approach is described. A fully dedicated network, consisting of three sensors, has been built. The system performance was evaluated and results are presented. View full abstract»

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  • Self-referencing multiplexing technique for fiber-optic intensity sensors

    Publication Year: 1987 , Page(s): 865 - 869
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1696 KB)  

    An all-optical technique for multiplexing and self-referencing a number of intensity modulating fiber-optic sensors is described. The optical transducers are fabricated as integral parts of recirculating optical fiber loops connected in parallel between transmit and receive optical fibers. A portion of an input pulse is tapped off by each sensor loop module. Successive fractions are tapped off on each circulation around the loop and transmitted to a detector. These form pulse trains that characterize each sensor's output. The relative magnitudes of the components of the pulse train are insensitive to lead and connector losses between the sensor modules and the source and detector. Time division multiplexing of the sensor return signals is created by the delays introduced by the fiber leads between the sensor modules. This paper details the response of a single sensor loop versus theoretical performance, and a three sensor system is demonstrated. View full abstract»

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  • Differential absorption fiber-optic liquid level sensor

    Publication Year: 1987 , Page(s): 941 - 946
    Cited by:  Papers (3)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2104 KB)  

    An optical fiber liquid level sensor based on differential optical absorption is described. The sensor uses a two-wavelength ratiometric approach to cancel out errors arising from variations in fuel characteristics, tank vibrations, etc. The sensor is mechanically simple and uses inexpensive LED sources and multimode optical fiber. The sensor displays ±2-mm resolution over an 18-cm range with immunity to 5° surface tilt variations and immunity to optical fiber connector and bending loss variations up to 1 dB. View full abstract»

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  • Multiplexing of interferometric sensors using phase carrier techniques

    Publication Year: 1987 , Page(s): 947 - 952
    Cited by:  Papers (9)  |  Patents (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2272 KB)  

    This paper demonstrates the multiplexing of fiber-optic interferometric sensors using a CW phase generated carrier technique. The technique employs modulated diode laser sources at different carrier frequencies, nearly balanced interferometers (∼4-cm path difference), and phase generated carrier demultiplexing demodulation. This approach leads to a simple all-passive sensor array which has intrinsically low crosstalk. The system is analyzed in terms of shot noise performance and crosstalk. An experimental all optical implementation of a four sensor array was demonstrated; both the single sensor and multisensor arrays were limited by the laser phase noise to a sensitivity of \sim 18 \mu rad/ \sqrt {Hz} . Crosstalk between individual channels was better than -60 dB and crosstalk between three sensors and the test sensor was better than -55 dB. In the absence of laser phase noise the demodulator/demultiplexer demonstrated \sim 2-\mu rad performance with both single sensor and four element array operation. View full abstract»

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  • An electric-field sensitive fiber with coaxial electrodes for optical phase modulation

    Publication Year: 1987 , Page(s): 926 - 931
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1992 KB)  

    It was shown that an electric-field sensitive optical fiber utilizing a radially poled piezoactive copolymer jacket is suitable for application as an all-fiber optical phase modulator. The jacket used was a copolymer of vinylidene fluoride and trifluoroethylene (P(VDF73/TrFE27)), 63-μm thickness, and was made radially piezoactive by corona discharge poling. The optical response of induced phase shift due to applied dc voltages was measured to be between 0.80 \times 10^{-5} and 1.24 \times 10^{-5} rad/(V/m) per meter of fiber. The performance of the jacketed fibers with coaxial electrodes as an optical phase modulator was tested over a wide frequency of range, from 20 Hz to 20 KHz. View full abstract»

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  • Deformation of single-mode optical fibers under static longitudinal stress

    Publication Year: 1987 , Page(s): 895 - 900
    Cited by:  Papers (7)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2048 KB)  

    The deformation of single-mode fibers resulting from a longitudinally applied static force has been measured experimentally by means of high resolution heterodyne interferometry and analyzed theoretically using the second-order theory of elasticity and the photoelastic effect. Both the elongation of the fiber and the phase change of light propagating through the fiber have been measured as a function of tensile force. The values of the elastic constants measured for fibers with pure silica core and B2O3doped cladding are E = 6.41 \times 10^{10} N/m2for the Young's modulus, \delta = -4.0 for the nonlinearity constant of the longitudinal strain, and \beta = -2.3 for the nonlinearity constant of the transverse strain. For unit elongations up to 0.3 percent, no creep, hysterisis, or relaxation effects have been observed within a resolution of one part in 104. View full abstract»

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  • Retardation characteristics of a bent birefringent fiber and its application to fiber-optic sensing techniques using polarization mode interference

    Publication Year: 1987 , Page(s): 1008 - 1013
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1712 KB)  

    Retardation characteristics dependent on the direction and the curvature of a bent birefringent fiber are presented. The deflection analysis of a cantilever model in elasticity is applied to the bent fiber. Based on the retardation characteristics, fundamental techniques concerned with the separation of the two measurand effects contained in the output signal, the vibration measurement, and the multiplexing of the sensor arrays in the polarization mode interferometric fiber-optic sensing are proposed. View full abstract»

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  • A digital fiber-optic liquid level sensor

    Publication Year: 1987 , Page(s): 920 - 925
    Cited by:  Papers (4)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2008 KB)  

    A fiber-optic liquid level sensor is presented which directly outputs digitally encoded liquid level information. The sensor operates on selective coupling at the liquid surface between a source waveguide and an array of digitally masked receiving waveguides. The receiving waveguides carry optical "high/low" signals to a remote detector and discriminator circuit. The sensor is capable of liquid level resolution of ± 2 mm over a range of up to several meters. A 40-cm-long prototype sensor has demonstrated an optical signal-to-noise ratio of 10-20 dB for several different transparent and semi-transparent liquids. The digital nature of the sensor provides good isolation from drift and the effect of tilt, source intensity fluctuations, and variations in liquid characteristics. Optical fibers are the only connections to the liquid tank, providing complete electrical isolation. The associated electronics are relatively simple and inexpensive. View full abstract»

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  • Optical integrated circuit for a fiber laser doppler velocimeter

    Publication Year: 1987 , Page(s): 901 - 905
    Cited by:  Papers (8)  |  Patents (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2016 KB)  

    In this paper, we propose and demonstrate a new optical integrated circuit (optical IC) pigtailed with a polarization-maintaining fiber for the laser Doppler velocimeter. In this optical IC, a waveguide frequency shifter, a TE/TM mode converter, and a mode splitter are integrated in Z -propagation Ti-diffused LiNbO3as well as a waveguide interferometer. Since the optical IC is as long as 32 mm, the waveguide patterning has been made with < 0.2-\mu m accuracy by a laser-beam lithographic system recently developed. Using the fabricated optical IC, the velocity of a moving object has been successfully heterodyne-detected with the signal-to-noise ratio of 25 dB. View full abstract»

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  • Optical vibrating quartz crystal pressure sensor using frustrated-total-internal-reflection readout technique

    Publication Year: 1987 , Page(s): 972 - 979
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2752 KB)  

    An optically driven, through photovoltaic conversion, pressure sensor is described which uses frustrated-total-internal-reflection between a critically cut optical fiber and a quartz crystal, mounted on a cantilever beam to sense the device resonant frequency. The change in this frequency as a function of applied pressure is measured in this sensor which relies upon an all-optical link to the control electronics. View full abstract»

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Aims & Scope

The Journal of Lightwave Technology contains articles on current research, applications and methods used in lightwave technology and fiber optics.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Peter J. Winzer
Alcatel-Lucent Bell Labs